Method and apparatus for controlling uplink power in a wireless access system

ABSTRACT

A method for reporting power headroom value in a wireless access system that supports a carrier aggregation, and a user equipment (UE) for performing the method are discussed. The method according to one embodiment includes receiving a uplink transmission grant allocating uplink resources on a predetermined subframe in an anchor uplink component carrier (UL CC); obtaining power headroom value for the anchor UL CC, if the UE is configured with a simultaneous physical uplink control channel (PUCCH) and physical uplink shared channel (PUSCH) transmission; and reporting the power headroom value to a base station. The power headroom value is calculated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of co-pending U.S. application Ser.No. 13/894,258 filed on May 14, 2013, which is a Continuation ofapplication Ser. No. 13/513,085 filed on Aug. 9, 2012 (granted as U.S.Pat. No. 8,462,705), which is a National Phase of PCT/KR2011/002286filed on Apr. 1, 2011, which claims priority under 35 U.S.C. §119(e) toU.S. Provisional Application Nos. 61/320,285 filed on Apr. 1, 2010 and61/324,728 filed on Apr. 15, 2010, all of which are hereby expresslyincorporated by reference into the present application.

BACKGROUND OF THE INVENTION Description of the Related Art

The present invention relates to a communication method and apparatusused in a wireless access system, and more particularly, to a method forreporting power headroom (PH) of a user equipment in a multicarrierenvironment and an apparatus for supporting the same.

In a general wireless access system, only a single carrier may beconsidered even though bandwidths between an uplink and a downlink areset up to be different from each other. For example, on the basis of asingle carrier, a wireless communication system may be provided, inwhich the number of carriers constituting the uplink and the number ofcarriers constituting the downlink may be 1, respectively, and abandwidth of the uplink is symmetrical to that of the downlink.

compared with a wireless communication system according to the relatedart. However, except for some areas of the world, it is difficult toallocate frequencies of wide bandwidths. Therefore, as a technique foreffectively using fragmented small bands, a carrier aggregation(bandwidth aggregation or spectrum aggregation) technique is beingdeveloped to obtain the same effect as when a band of a logically widebandwidth is used by physically aggregating a plurality of bands in afrequency domain.

The carrier aggregation is introduced to support increased throughput,prevent the cost from being increased by a wideband RF device, andensure compatibility with the existing system. The carrier aggregationrefers to a technique of enabling data exchange between a user equipmentand a base station through a plurality of groups of carriers of abandwidth unit defined in the existing wireless communication system.

In this case, the carriers of a bandwidth unit defined in the existingwireless communication system may be referred to as component carriers(CC). For example, the carrier aggregation technique may include atechnique for supporting a system bandwidth of maximum 100 MHz by usingmaximum five component carriers even if one component carrier supports abandwidth of 5 MHz, 10 MHz or 20 MHz.

If the carrier aggregation technique is used, data may simultaneously betransmitted and received through several uplink/downlink componentcarriers. Accordingly, the user equipment may monitor and measure allthe component carriers.

In the existing communication system, it was sufficient to report theresidual quantity of an uplink transmission power of a user equipmentfor one carrier. However, as a communication environment is developed, acarrier matching technology that two or more carriers are matched withone another is required to cover a frequency range of maximum 100 MHz.

Accordingly, when a user equipment has a plurality of uplink componentcarriers (that is, serving cell), it is required that a technology forreporting power headroom (PH) of a user equipment should be developed ina different manner of the existing method.

An object of the present invention devised to solve the conventionalproblem is to provide various methods for reporting power headroom of auser equipment in a carrier matching multi-carrier environment andapparatuses for supporting the same.

It will be appreciated by persons skilled in the art that the objectsthat could be achieved with the present invention are not limited towhat has been particularly described hereinabove and the above and otherobjects that the present invention could achieve will be more clearlyunderstood from the following detailed description.

To solve the aforementioned technical problem, the present inventionprovides a method for reporting power headroom (PH) of a user equipmentin a multicarrier environment and apparatuses for supporting the same.

In one aspect of the present invention, a method for reporting powerheadroom of a user equipment of a multi-carrier system comprises thesteps of receiving a physical downlink control channel (PDCCH) signalcomprising uplink resource allocation information from a base station;transmitting at least one of a physical uplink shared channel (PUSCH)signal and the physical uplink control channel (PUCCH) signal to thebase station for a predetermined subframe on the basis of the uplinkresource allocation information in accordance with a transmission mode;calculating one or more power headroom values for the predeterminedsubframe in accordance with the transmission mode; and reporting the oneor more power headroom values to the base station, wherein the userequipment reports a first type power headroom value and a second typepower headroom value for the predetermined subframe when the userequipment operates in transmission mode A, and reports its first typepower headroom value when the user equipment operates in transmissionmode B.

In another aspect of the present invention, the method may furthercomprise transmitting a physical downlink control channel (PDCCH) signalcomprising uplink resource allocation information to the user equipment,receiving at least one of a physical uplink shared channel (PUSCH)signal and the physical uplink control channel (PUCCH) signal for apredetermined subframe on the basis of the uplink resource allocationinformation in accordance with a transmission mode of the userequipment, and receiving a report message (for example, extended powerheadroom MAC control element) comprising one or more power headroomvalues from the user equipment. In this case, the one or more powerheadroom values may be calculated in accordance with the transmissionmode of the user equipment, and if the user equipment operates in thetransmission mode A, the power headroom value may be a first type powerheadroom value and a second type power headroom value for thepredetermined subframe, and if the user equipment operates in thetransmission mode B, the power headroom value may be the first typepower headroom value.

In still another aspect of the present invention, a user equipment forperforming power headroom report in a multi-carrier system comprises areception module for receiving a channel signal; a transmission modulefor transmitting the channel signal; and a processor supporting afunction for performing the power headroom report.

In this case, the user equipment receives a physical downlink controlchannel (PDCCH) signal comprising uplink resource allocation informationfrom a base station by using the reception module, transmits at leastone of a physical uplink shared channel (PUSCH) signal and the physicaluplink control channel (PUCCH) signal to the base station through thetransmission module for a predetermined subframe on the basis of theuplink resource allocation information in accordance with a transmissionmode, calculates one or more power headroom values for the predeterminedsubframe through the processor, reports the one or more power headroomvalues to the base station through the transmission module in accordancewith the transmission mode. In particular, the user equipment reportsits first type power headroom value and second type power headroom valuefor the predetermined subframe to the base station when the userequipment operates in transmission mode A, and reports its first typepower headroom value to the base station when the user equipmentoperates in transmission mode B.

In further still another aspect of the present invention, a base stationsupporting a power headroom report method in a multi-carrier systemcomprises a reception module for receiving a channel signal, atransmission module for transmitting the channel signal, and a processorsupporting a function for supporting power headroom report.

The base station transmits a physical downlink control channel (PDCCH)signal comprising uplink resource allocation information to a userequipment by using the reception module, receives at least one of aphysical uplink shared channel (PUSCH) signal and the physical uplinkcontrol channel (PUCCH) signal from the user equipment through thereception module for a predetermined subframe on the basis of the uplinkresource allocation information in accordance with a transmission mode,and receives a report message comprising one or more power headroomvalues for the predetermined subframe from the user equipment throughthe reception module. At this time, the one or more power headroomvalues are reported in accordance with the transmission mode of the userequipment. In particular, when the user equipment operates intransmission mode A, the power headroom value may be the first typepower headroom value and the second type power headroom value for thepredetermined subframe, and when the user equipment operates intransmission mode B, the power headroom value may be the first typepower headroom value.

In the above aspects of the present invention, if the user equipmentoperates in the transmission mode A, it transmits the PUSCH signal andthe PUCCH signal to the base station for the predetermined subframe of aprimary (P) cell, and if the user equipment operates in the transmissionmode B, it transmits the PUSCH signal to the base station for thepredetermined subframe of a serving cell.

In the transmission mode A, the PUCCH signal and the PUSCH signal may besimultaneously transmitted through a PUCCH region and a PUSCH region,respectively, and in the transmission mode B, the PUCCH signal may besubjected to piggyback into the PUSCH signal and transmitted through thePUSCH region.

At this time, the first type power headroom value may be calculatedusing a maximum transmission power of the user equipment and atransmission power of the PUSCH signal, and the second type powerheadroom value may be calculated using the maximum transmission power ofthe user equipment, the transmission power of the PUSCH signal, and atransmission power of the PUCCH signal.

Also, the first type power headroom value may be calculated using adifference value between the maximum transmission power of the userequipment and the transmission power of the PUSCH signal, and the secondtype power headroom value may be calculated using a difference valuebetween the maximum transmission power of the user equipment and the sumof the transmission power of the PUSCH signal, and the transmissionpower of the PUCCH signal.

In the above aspects of the present invention, the second type powerheadroom may be calculated as expressed by Equation 2. At this time,P_(CMAXc) represents the maximum transmission power of the userequipment, P_(PUSCH) _(—) _(scheduled)(i) represents the transmissionpower of the PUSCH signal, and P_(PUCCH) _(—) _(scheduled(i)) representsthe transmission power of the PUCCH signal. Also, the second type powerheadroom value may be calculated using the transmission power of thePUCCH signal even though the PUCCH signal is not transmitted for thepredetermined subframe. At this time, the second type power headroomvalue may be calculated as expressed by Equation 6. Also, the first typepower headroom value may be calculated using Equation 1.

In the above aspects of the present invention, the report message mayfurther include a maximum transmission power value at a primary (P) cellor serving cell of the user equipment.

The aspects of the present invention are only a part of the preferredembodiments of the present invention, and various embodiments based ontechnical features of the present invention may be devised andunderstood by the person with ordinary skill in the art based on thedetailed description of the present invention.

SUMMARY OF THE INVENTION

According to the embodiments of the present invention, the followingadvantages may be obtained.

If one or more serving cells are allocated to a user equipment, uplinkresources may efficiently be allocated to the user equipment by usingvarious methods for reporting power headroom of the user equipment foreach cell.

Also, in a carrier aggregation environment, the method for reportingpower headroom of a user equipment may be used if the user equipment isallocated with one or more cells. Accordingly, even in the case thatPUCCH and PUSCH signals are simultaneously transmitted, the method forreporting power headroom of a user equipment may be used efficiently.

It will be appreciated by persons skilled in the art that that theeffects that could be achieved with the present invention are notlimited to what has been particularly described hereinabove and otheradvantages of the present invention will be more clearly understood fromthe following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a structure of a radio frame that maybe used in the embodiments of the present invention;

FIG. 2 is a diagram illustrating a resource grid for one downlink slotthat may be used in the embodiments of the present invention;

FIG. 3 is a diagram illustrating a structure of a downlink subframe thatmay be used in the embodiments of the present invention;

FIG. 4 is a diagram illustrating a structure of an uplink subframe thatmay be used in the embodiments of the present invention;

FIG. 5 is a diagram illustrating an example of a component carrier (CC)of an LTE system and multicarrier aggregation (carrier aggregation) usedin an LTE-A system;

FIG. 6 is a diagram illustrating a case where a PUCCH signal issubjected to piggy back in a PUSCH region;

FIG. 7 is a diagram illustrating a method for transmitting a PUCCHsignal and a PUSCH signal of a user equipment in accordance with atransmission mode;

FIG. 8 is a diagram illustrating an example of a method for reportingpower headroom of a user equipment based on a transmission mode inaccordance with the embodiment of the present invention;

FIG. 9 is a diagram illustrating an example of an apparatus forsupporting a method for reporting power headroom, which is disclosed inthe present invention, in accordance with the embodiment of the presentinvention; and

FIG. 10 is a diagram illustrating another example of an apparatus forsupporting a method for reporting power headroom, which is disclosed inthe present invention, in accordance with the embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

The embodiments of the present invention disclose various methods forreporting power headroom (PH) of a user equipment in a multicarrierenvironment and apparatuses for supporting the same.

The following embodiments are achieved by combination of structuralelements and features of the present invention in a predetermined type.Each of the structural elements or features should be consideredselectively unless specified separately. Each of the structural elementsor features may be carried out without being combined with otherstructural elements or features. Also, some structural elements and/orfeatures may be combined with one another to constitute the embodimentsof the present invention. The order of operations described in theembodiments of the present invention may be changed. Some structuralelements or features of one embodiment may be included in anotherembodiment, or may be replaced with corresponding structural elements orfeatures of another embodiment.

In the description of drawings, procedures or steps that may make thesubject matter of the present invention obscure will not be disclosed.Also, procedures or steps that may be understood by the person withordinary skill in the art will not be disclosed.

In this specification, the embodiments of the present invention havebeen described based on the data transmission and reception between abase station and a mobile station. In this case, the base station meansa terminal node of a network, which performs direct communication withthe mobile station. A specific operation which has been described asbeing performed by the base station may be performed by an upper node ofthe base station as the case may be.

In other words, it will be apparent that various operations performedfor communication with the mobile station in the network which includesa plurality of network nodes along with the base station may beperformed by the base station or network nodes other than the basestation. At this time, the base station (BS) may be replaced with termssuch as a fixed station, Node B, eNode B (eNB), an advanced base station(ABS), and an access point (AP).

Also, the mobile station may be replaced with terms such as a userequipment (UE), a subscriber station (SS), a mobile subscriber station(MSS), an advanced mobile station (AMS) or a terminal.

Furthermore, a transmitting side means a fixed or mobile node thattransmits data services or voice services while a receiving side means afixed or mobile node that receives data services or voice services.Accordingly, in an uplink, the mobile station could be a transmittingside while the base station could be a receiving side. Likewise, in adownlink, the mobile station could be a receiving side while the basestation could be a transmitting side.

The embodiments of the present invention may be supported by standarddocuments disclosed in at least one of wireless access systems, i.e.,IEEE 802 system, 3GPP system, 3GPP LTE system, and 3GPP2 system.Particularly, the embodiments of the present invention may be supportedby one or more of documents of 3GPP TS 36.211, 3GPP TS 36.212, 3GPP TS36.213, and 3GPP TS 36.321. Namely, among the embodiments of the presentinvention, steps or parts which are not described to clarify thetechnical features of the present invention may be supported by theabove standard documents. Also, all terminologies disclosed herein maybe described by the above standard documents.

Hereinafter, the preferred embodiments of the present invention will bedescribed with reference to the accompanying drawings. It is to beunderstood that the detailed description, which will be disclosed alongwith the accompanying drawings, is intended to describe the exemplaryembodiments of the present invention, and is not intended to describe aunique embodiment with which the present invention can be carried out.

Specific terminologies hereinafter used in the embodiments of thepresent invention are provided to assist understanding of the presentinvention, and various modifications may be made in the specificterminologies within the range that they do not depart from technicalspirits of the present invention.

The following technology may be used for various wireless access systemssuch as CDMA (code division multiple access), FDMA (frequency divisionmultiple access), TDMA (time division multiple access), OFDMA(orthogonal frequency division multiple access), and SC-FDMA (singlecarrier frequency division multiple access).

The CDMA may be implemented by the radio technology such as universalterrestrial radio access (UTRA) or CDMA2000. The TDMA may be implementedby the radio technology such as global system for mobile communications(GSM)/general packet radio service (GPRS)/enhanced data rates for GSMevolution (EDGE). The OFDMA may be implemented by the radio technologysuch as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, andevolved UTRA (E-UTRA).

The UTRA is a part of a universal mobile telecommunications system(UMTS). A 3^(rd) generation partnership project long term evolution(3GPP LTE) communication system is a part of an evolved UMTS (E-UMTS)that uses E-UTRA, and uses OFDMA in a downlink while uses SC-FDMA in anuplink. LTE-advanced (LTE-A) is an evolved version of the 3GPP LTEsystem. Although the following description will be based on the 3GPPLTE/LTE-A to clarify description of technical features, it is to beunderstood that technical spirits of the present invention are notlimited to the 3GPP LTE/LTE-A.

1. Basic Structure of 3GPP LTE/LTE-A System

FIG. 1 is a diagram illustrating a structure of a radio frame that maybe used in the embodiments of the present invention.

A radio frame includes ten (10) subframes, each of which includes twoslots. The time required to transmit one subframe will be defined as atransmission time interval (TTI). At this time, one subframe has alength of 1 ms, and one slot has a length of 0.5 ms.

One slot includes a plurality of orthogonal frequency divisionmultiplexing (OFDM) symbols in the time domain and a plurality ofresource blocks (RBs) in a frequency domain. The OFDM symbols representone symbol period in the 3GPP LTE system that uses an orthogonalfrequency division multiplexing access (OFDMA) scheme in a downlink.Namely, the OFDM symbols may be referred to as SC-FDMA symbols or symbolduration depending on multiple access system. A resource block (RB) is aresource allocation unit, and includes a plurality of continuoussubcarriers in one slot.

The structure of the radio frame in FIG. 1 is only exemplary, andvarious modifications may be made in the number of subframes included inthe radio frame, the number of slots included in one subframe, or thenumber of OFDM symbols included in one slot.

FIG. 2 is a diagram illustrating a resource grid for one downlink slotthat may be used in the embodiments of the present invention.

The downlink slot includes a plurality of OFDM symbols in a time domain.In an example of FIG. 2, one downlink slot includes seven OFDM symbols,and one resource block includes 12 subcarriers in a frequency domain.

Each element on a resource grid will be referred to as a resourceelement (RE). One resource block (RB) includes 12×7 resource elements(REs). The number N^(DL) of resource blocks included in the downlinkslot is subjected to a downlink transmission bandwidth set in a cell.

FIG. 3 is a diagram illustrating a structure of a downlink subframe thatmay be used in the embodiments of the present invention.

The downlink subframe includes two slots in a time domain. Maximum threeOFDM symbols located at the front of the first slot within one downlinksubframe correspond to a control region to which control channels areallocated. The other OFDM symbols correspond to a data region to which aphysical downlink shared channel (PDSCH) is allocated.

Examples of downlink control channels used in the 3GPP LTE systeminclude a Physical Control Format Indicator Channel (PCFICH), a PhysicalDownlink Control Channel (PDCCH), and a Physical Hybrid ARQ IndicatorChannel (PHICH). The PCFICH signal transmitted from the first OFDMsymbol of the subframe carries information on the number (that is, sizeof control region) of OFDM symbols used for transmission of the controlchannels within the subframe. The PHICH carries ACK/NACK(acknowledgement/negative-acknowledgement) signal in response to uplinkHARQ (Hybrid Automatic Repeat Request). In other words, the ACK/NACKsignal for the uplink data transmitted from the user equipment istransmitted onto the PHICH.

The control information transmitted through the PDCCH will be referredto as downlink control information (DCI). The DCI includes resourceallocation information for user equipment or user equipment group andother control information. For example, the DCI may include uplinkresource allocation information, downlink resource allocationinformation and uplink transmission power control command.

The PDCCH may carry transport format and resource allocation informationof a downlink shared channel (DL-SCH), transport format and resourceallocation information of an uplink shared channel (UL-SCH), paginginformation on a paging channel (PCH), system information on the DL-SCH,resource allocation information of upper layer control message such asrandom access response transmitted on the PDSCH, a set of transmissionpower control commands of individual user equipments (UEs) within arandom user equipment group, transmission power control command, andactivity information of voice over Internet protocol (VoIP).

A plurality of PDCCHs may be transmitted from one control region. Theuser equipment may monitor the plurality of PDCCHs. The PDCCH istransmitted on one or more continuous control channel elements (CCEs).The CCE is a logic allocation resource used to provide the PDCCH at asingle coding rate based on the status of a radio channel. The CCEcorresponds to a plurality of resource element groups (REGs). The formatof the PDCCH and the number of available bits of the PDCCH aredetermined depending on the correlation between the number of CCEs andthe coding rate provided by the CCE. The base station determines a PDCCHformat depending on the DCI to be transmitted to the user equipment, andattaches cyclic redundancy check (CRC) to the control information.

The CRC is masked with an identifier (for example, radio networktemporary identifier (RNTI)) depending on usage of the PDCCH or owner ofthe PDCCH. If the PDCCH is for a specific user equipment, an identifier(for example, cell-RNTI (C-RNTI)) of the corresponding user equipmentmay be masked with the CRC. If the PDCCH is for a paging message, apaging identifier (for example, Paging-RNTI (P-RNTI)) may be masked withthe CRC. Also, if the PDCCH is for system information (in more detail,system information block (SIB)), a system information identifier andsystem information RNTI (S-RNTI) may be masked with the CRC. In order toindicate a random access response which is the response to reception ofa random access preamble of the user equipment, a random access RNTI(RA-RNTI) may be masked with the CRC.

The PDCCH may be transmitted through one or more component carriers in acarrier aggregation environment, and may include resource allocationinformation on one or more component carriers. For example, although thePDCCH is transmitted through one component carrier, it may includeresource allocation information on one or more PDSCHs and PUSCHs.

FIG. 4 is a diagram illustrating an example of a structure of an uplinksubframe that may be used in the embodiments of the present invention

Referring to FIG. 4, the uplink subframe includes a plurality of slots(for example, two slots). The slot may include a number of SC-FDMAsymbols different from the number of SC-FDMA symbols of the other slot.The uplink subframe may be divided into a control region and a dataregion on a frequency domain. The data region includes a physical uplinkshared channel (PUSCH), and is used to transmit a data signal thatincludes voice information. The control region includes a physicaluplink control channel (PUCCH), and is used to transmit uplink controlinformation (UCI). The PUCCH includes RB pair located at both ends ofthe data region on the frequency axis and performs hopping at a slotboundary. In the LTE system, in order to maintain single carrierfeatures, the user equipment does not transmit the PUCCH signal and thePUSCH signal at the same time.

The PUCCH for one user equipment is allocated to resource block (RB)pair for one subframe. Resource blocks (RBs) belonging to the RB pairoccupy different subcarriers for two slots. It means that the RB pairallocated to the PUCCH is subjected to frequency hopping at a slotboundary.

The PUCCH may be used to transmit the following control information.

-   -   SR (Scheduling Request): is information used to request uplink        UL-SCH resource. The SR is transmitted using an on-off keying        (OOK) system.    -   HARQ ACK/NACK: is a response signal to a downlink data packet on        the PDSCH. It represents whether the downlink data packet has        been successfully received. ACK/NACK 1 bit is transmitted in        response to a single downlink codeword, and ACK/NACK 2 bits are        transmitted in response to two downlink codewords.    -   CQI (Channel Quality Indicator): is feedback information on a        downlink channel. MIMO (Multiple Input Multiple Output) related        feedback information includes a rank indicator (RI) and a        precoding matrix indicator (PMI). 20 bits are used per subframe.

The quantity of the uplink control information (UCI) that may betransmitted from the user equipment for the subframe depends on thenumber of SC-FDMA symbols available for control informationtransmission. The SC-FDMA symbols available for control informationtransmission mean the remaining SC-FDMA symbols except for SC-FDMAsymbols for reference signal transmission for the subframe, and the lastSC-FDMA symbols of the subframe is excluded in case of the subframe forwhich a sounding reference signal (SRS) is set. The reference signal isused for coherent detection of the PUCCH. The PUCCH supports sevenformats in accordance with information which is transmitted.

Table 1 illustrates a PUCCH format and a mapping relation of UCI in theLTE.

TABLE 1 PUCCH format UCI Format 1 Scheduling request (SR) Format 1a 1bit HARQ ACK/NACK that includes SR or does not include SR Format 1b 2bit HARQ ACK/NACK that includes SR or does not include SR Format 2CQI(20 coded Bits) Format 2 CQI and 1 or 2 bit HARQ ACK/NACK forextended CP Format 2a CQI and 1 bit HARQ ACK/NACK Format 2b CQI and 2bit HARQ ACK/NACK

2. Multi-Carrier Environment

A communication environment considered by the embodiments of the presentinvention includes a multi-carrier environment. In other words, amulti-carrier system or carrier aggregation system used in the presentinvention means a system that one or more carriers having a bandwidthsmaller than a target bandwidth are aggregated when a target wideband isconfigured to support a wideband.

In the present invention, multi-carrier means aggregation of carriers(or carrier aggregation). At this time, carrier aggregation meansaggregation between non-neighboring carriers as well as aggregationbetween neighboring carriers. Also, carrier aggregation may be used torefer to bandwidth aggregation.

Multi-carrier (that is, carrier aggregation) configured by aggregationof two or more component carriers (CC) aims to support a bandwidth of100 MHz in the LTE-A system. When one or more carriers having abandwidth smaller than a target bandwidth are aggregated, a bandwidth ofthe aggregated carriers may be limited to a bandwidth used in theexisting system to maintain backward compatibility with the existing IMTsystem.

For example, the 3GPP LTE system (LTE R-8 system) supports bandwidths of{1.4, 3, 5, 10, 15, 20} MHz, and the 3GPP LTE_advanced system (that is,LTE_A) may support a bandwidth greater than 20 MHz using the abovebandwidths supported by the LTE system. Also, the multi-carrier systemused in the present invention may support carrier aggregation bydefining a new bandwidth regardless of the bandwidth used in theexisting system.

FIG. 5 is a diagram illustrating an example of a component carrier (CC)of an LTE system and multicarrier aggregation (carrier aggregation) usedin an LTE-A system.

FIG. 5( a) illustrates a single carrier structure used in the LTEsystem. The component carrier includes a downlink component carrier (DLCC) and an uplink component carrier (UL CC). One component carrier mayhave a frequency range of 20 MHz.

FIG. 5( b) illustrates a multi-carrier structure used in the LTE_Asystem. In FIG. 5( b), three component carriers having a frequency sizeof 20 MHz are aggregated. In case of multi-carrier aggregation, the userequipment may monitor three component carriers at the same time, receivedownlink signal/data and transmit uplink signal/data.

If N DL CCs are managed by a specific base station (eNB: e-NodeB)region, the network may allocate M (M≦N) number of DL CCs to the userequipment. At this time, the user equipment may monitor M number oflimited DL CCs only and receive DL signal. Also, the network may give L(L≦M≦N) number of DL CCs a priority and allocate them to the userequipment as main DL CCs. In this case, the user equipment should Lnumber of DL CCs necessarily. This system may also be applied to uplinktransmission.

The LTE-A system uses a concept of cell to manage a radio resource. Thecell is defined by combination of downlink resources and uplinkresources, wherein the uplink resources may be defined selectively. Forexample, the cell may be configured by downlink resources only, or maybe configured by downlink resources and uplink resources. Ifmulti-carrier (that is, carrier aggregation) is supported, linkagebetween carrier frequency (or DL CC) of the downlink resources andcarrier frequency (or UL CC) of the uplink resources may be indicated bysystem information. In other words, one cell may include one or moredownlink component carriers, and may selectively include one or moreuplink component carriers.

The cell used in the LTE-A system includes a primary cell (PCell) and asecondary cell (SCell). The P cell may mean a cell operated on theprimary frequency (or primary CC), and the S cell may mean a celloperated on the secondary frequency (or secondary CC). However, a singleP cell may be allocated to a specific user equipment and one or more Scells may be allocated to the specific user equipment.

The P cell is used such that the user equipment performs an initialconnection establishment procedure or connection re-establishmentprocedure. The P cell may refer to a cell indicated during a handoverprocedure. The S cell may be configured after RRC connection isestablished, and may be used to provide an additional radio resource.

The P cell and the S cell may be used as serving cells. Although theuser equipment is in RRC-CONNECTED state, if it is not set by carrieraggregation or does not support carrier aggregation, a single servingcell configured by the P cell exists. On the other hand, if the userequipment is in the RRC-CONNECTED state and is set by carrieraggregation, one or more serving cells may exist, wherein the servingcells may include a P cell and one or more S cells.

After an initial security activity procedure starts, the E-UTRAN mayconfigure a network that includes one or more S cells in addition to a Pcell initially configured during a connection establishment procedure.In the multi-carrier environment, the P cell and the S cell may beoperated as component carriers, respectively. In other words, carriermatching may be understood by aggregation of the P cell and one or moreS cells. In the following embodiment, the primary component carrier(PCC) may be used to refer to the P cell, and the secondary componentcarrier (SCC) may be used to refer to the S cell.

FIG. 6 is a diagram illustrating a case where a PUCCH signal issubjected to piggy back in a PUSCH region.

Referring to FIG. 6, the first subframe illustrates that a PUCCH signaland a PUSCH signal are transmitted at the same time, and the second andthird subframes illustrate that the PUCCH signal and the PUSCH signalare respectively transmitted from the PUCCH region and the PUSCH region.

However, in the 3GPP LTE system (R-8), in case of uplink, in order toefficiently use a power amplifier of the user equipment, it ispreferable to maintain single carrier property having goodpeak-to-average power ratio (PAPR) feature or good cubic metric (CM)feature, wherein the PAPR feature acts on throughput of the poweramplifier.

For example, if the user equipment transmits the PUSCH signal, thesingle carrier property may be maintained through DFT-precoding for datawhich will be transmitted. If the user equipment transmits the PUCCHsignal, the single carrier property may be maintained in such a mannerthat the PUCCH signal is carried in the sequence having the singlecarrier property.

However, if the DFT-precoded data are allocated discontinuously on thefrequency axis, or if the PUSCH signal and the PUCCH signal aretransmitted at the same time, the single carrier property may beremoved. Accordingly, if PUSCH transmission is performed for the samesubframe as that for PUCCH transmission as shown in FIG. 6, uplinkcontrol information (UCI) which will be transmitted to the PUCCH may besubjected to piggyback together with general data through the PUSCH,whereby the single carrier property may be maintained.

3. Power Headroom Report Method

In order that the base station (eNB: eNode-B) properly schedules uplinktransmission resources for a plurality of user equipments, it ispreferable that each user equipment reports its possible power headroominformation to the base station. The base station may use the powerheadroom report (PHR) received from each user equipment to determine anavailable uplink bandwidth per subframe. This method may properlydistribute the uplink resources allocated to the user equipment, wherebyeach user equipment may be prevented from being allocated withunnecessary uplink resources.

The power headroom report is performed in 1 dB unit, and is in the rangeof 40 dB to −23 dB. In this case, the range of ‘−’ value represents therange that each user equipment transmit a signal to the base stationusing transmission power more than that allocated through UL grant.

The PHR may allow the base station to reduce the size (that is, thenumber of RBs in the frequency domain) of next UL grant, and may releasetransmission resources which will be transmitted to the other userequipments. The PHR may be transmitted for the subframe having uplinktransmission grant. The PHR is related with the subframe for which thePHR is transmitted.

In the 3GPP LTE system, a method for calculating a PHR value in a userequipment is as expressed by the following Equation 1.

PH(i)=P _(CMAX)−{10 log₁₀(M _(PUSCH)(i))+P _(O) _(—)_(PUSCH)(j)+α(j)·PL+Δ _(TF)(i)+f(i)}  [Equation 1]

In this case, P_(CMAX) represents a theoretical maximum transmissionpower of the user equipment, and M_(PUSCH)(i) is a parameter indicatinga bandwidth of PUSCH resource allocation expressed as the number ofeffective resource blocks for the subframe of index i and is a valueallocated from the base station.

P_(O) _(—) _(PUSCH)(j) is a parameter configured by the sum of acell-specific nominal component P_(O) _(—) _(NOMINAL) _(—) _(PUSCH)(j)provided from the upper layer and a user equipment-specific componentP_(O) _(—) _(UE) _(—) _(PUSCH)(j) provided from the upper layer, and isa value notified from the base station to the user equipment.

α(j) is a cell-specific parameter provided from the upper layer andtransmitted by the base station as 3 bits, and when j=0 or 1, αε{0, 0.4,0.5, 0.6, 0.7, 0.8, 0.9, 1}, and when j=2, α(j)=1. α(j) is a valuenotified from the base station to the user equipment.

PL is an estimated value of downlink path loss (PL: PathLoss) calculatedby the user equipment in a unit of dB, and is expressed asPL=referenceSignalPower−higher layer filteredRSRP. f(i) is a valueindicating the current PUSCH power control adjustment state, and may beexpressed as a current absolute value or accumulated value.

The power headroom (PH) is configured by 64 level value of 1 dB intervalbetween −23 dB and 40 dB, and is forwarded from the physical layer tothe upper layer. The PH MAC control element is identified by the MAC PDUsubheader.

4. Power Headroom Report Method I in Carrier Aggregation Environment

In a carrier aggregation environment, one or more serving cells may beallocated to each user equipment. One of the serving cells may be a Pcell. In this case, in the LTE-A system, it is preferable that the userequipment performs a PHR procedure for one or more serving cells unlikethe existing LTE system. Accordingly, a method for performing a PHRprocedure when P cell and one or more S cells are allocated to a userequipment will hereinafter be described in detail.

The PHR procedure means that the user equipment calculates a PH for acell allocated from its physical layer and reports the calculated PH tothe base station.

For example, the user equipment may provide the base station withinformation (for example, first type ePH value) on the differencebetween the theoretical maximum transmission power of the user equipmentat each activated serving cell and a transmission power of the userequipment, which is measured for the uplink shared channel (UL-SCH,PDSCH, etc.).

Also, the user equipment may provide the base station with information(for example, second type ePH value) on the difference between thetheoretical maximum transmission power of the user equipment and atransmission power of the user equipment, which is measured for theuplink shared channel (UL-SCH) and the PUCCH at the P cell, andinformation (for example, second type ePH value) on the differencebetween the theoretical maximum transmission power of the user equipmentand a transmission power of the user equipment, which is measured forthe uplink shared channel (UL-SCH, PDSCH, etc.).

The embodiments of the present invention are applied to the LTE-Asystem, and the PHR of the present invention will be referred to as anextended PHR (ePHR) to distinguish the PHR of the existing LTE R-8 fromthe PHR of the present invention. In other words, the user equipment maytransmit the first type ePH value to the base station in the servingcell and transmit the first type ePH value and the second ePH value tothe base station in the P cell to perform the ePHR procedure. At thistime, the user equipment may transmit the PH values to the base stationtogether with the information on the maximum transmission power of theuser equipment.

For example, the physical layer of the user equipment calculates a powerheadroom (first type ePH) value for the PUSCH of the activated servingcell, and forwards the first type ePH value and information on themaximum transmission power P_(MAX,c) of the user equipment to the upperlayer (for example, MAC or RRC layer) of the user equipment. The upperlayer of the user equipment may transmit the first type ePH and theinformation on P_(MAX,c) to the base station.

Also, the physical layer of the user equipment may calculate the firsttype ePH, the second type ePH and the maximum transmission powerP_(MAX,c) of the user equipment at the activated P cell and forward thecalculated values to the upper layer of the user equipment, and theupper layer of the user equipment may transmit the second type PHRinformation and information on P_(MAX,c) to the base station.

FIG. 7 illustrates that the user equipment transmits a data signal and acontrol signal using three serving cells (e.g., UL CC). In FIG. 7, ULCC1 represents a P cell, and the user equipment may transmit a controlsignal (UCI, that is, PUCCH signal) and a data signal (for example,PUSCH signal) through the P cell. Also, UL CC2 and UL CC3 represent theS cells, and the user equipment may transmit the PUSCH signal throughthe S cell. At this time, FIG. 7( a) illustrates that the user equipmentis operated in accordance with mode A, and FIG. 7( b) illustrates thatthe user equipment is operated in accordance with mode B.

The mode A illustrates that the user equipment may simultaneouslytransmit the PUSCH signal and the PUCCH signal for the same subframe.For example, the user equipment of the mode A transmits the PUCCH signaland the PUSCH signal for the first subframe of the P cell (that is, ULCC1) at the same time, transmits the PUCCH signal only for the secondsubframe, and transmits the PUSCH signal only for the third subframe.Also, the user equipment may transmit the PUSCH signal through the PUSCHregion at the S cell (that is, UL CC2 and UL CC3).

The mode B illustrates that user equipment does not simultaneouslytransmit the PUSCH signal and the PUCCH signal for the same subframe.For example, the user equipment of the mode B may transmit the PUCCHsignal (UCI) at the UL CC1 (serving cell) through piggybacking ormultiplexing the signal into the PUSCH signal. In other words, the userequipment may transmit the control signal (e.g., UCI) through piggybackwith the data signal in the PUSCH region without transmitting thecontrol signal through the PUCCH region.

Accordingly, if the user equipment is configured by the mode A, it maycalculate the first type power headroom value and the second type powerheadroom value and report the calculated values to the base station.Also, if the user equipment is configured by the mode B, it maycalculate the first type power headroom value and report the calculatedvalue to the base station.

Although the method for transmitting the uplink control signal and datasignal in the P cell has been described in FIG. 7, the control signaland data signal may be transmitted in an arbitrary serving cell which isnot the P cell. Hereinafter, in the case where the PUSCH signal and thePUCCH signal are simultaneously transmitted in a specific serving celllike the mode A and the case where the PUCCH signal is piggybacked intothe PUSCH signal in a specific serving cell like the mode B, a methodfor transmitting power headroom report (PHR) from a user equipment to abase station will be described.

FIG. 8 is a diagram illustrating an example of a method for reportingpower headroom of a user equipment based on a transmission mode inaccordance with the embodiment of the present invention.

The user equipment UE may negotiate with the base station eNB throughupper layer signaling as to which mode is used to operate the userequipment. In other words, the user equipment may be operated by thetransmission mode A or B described in FIG. 7 in accordance with thenegotiation result with the base station.

The user equipment UE may receive a PDCCH signal, which includes uplinkresource allocation information (e.g., UL grant) on one or more servingcells, in a carrier aggregation (CA) environment (S810).

At the step S810, the user equipment may be allocated with one or morecells (that is, one or more CCs). At this time, the user equipment maybe operated by the same transmission mode or independent transmissionper allocated cell.

The user equipment may perform communication with the base stationthrough the allocated uplink. In other words, the user equipment maytransmit PUCCH and/or PUSCH signals to the base station in accordancewith the mode A or B for the i-th subframe in one or more cells (S820).

If any one condition of the following events is satisfied, the userequipment may trigger the ePHR procedure. In other words, the userequipment may calculate the first type ePH and/or the second type ePH if(1) a first timer (for example, prohibitPHR-Timer) prohibiting the powerheadroom report (PHR) expires or the first timer expires in at least oneactivated serving cell and change of transmission path loss is greaterthan a previously set value (for example, DL_PathlossChange dB), (2) ifa periodic report timer which is a second timer (for example, aPeriodicPHR-Timer) expires, or (3) if a secondary (S) cell having anuplink is activated (S830).

If the user equipment is operated by the transmission mode B, it mayreport the first type ePH for the current subframe (i) of the servingcell c to the base station. Also, if the user equipment is operated bythe transmission mode A, it may report the first type ePH and the secondtype ePH for the current subframe (i) of the primary (P) cell to thebase station.

At the step S830, the first type ePH and/or the second ePH arecalculated by the physical layer of the user equipment and thenforwarded to the upper layer (for example, MAC layer and/or RRC layer)of the user equipment. For the PHR procedure, the upper layer of theuser equipment receives one or more ePH values from the physical layerand reports the received ePH values to the base station. At this time,the user equipment may transmit the ePH values to the base stationtogether with the maximum transmission power value of the userequipment, which is used when each ePH is calculated (S840).

At the step S840, the user equipment may transmit one or more ePH valuesto the base station by using an extended power headroom MAC controlelement (for example, report message). Also, if the user equipment isallocated with one or more cells, it may report the ePH for each celland its maximum transmission power to the base station.

The base station may schedule uplink radio resources based on the one ormore ePH values received from each user equipment and allocate thescheduled radio resources to each user equipment. Also, the base stationtransmits a PDCCH signal, which includes UL grant, to each userequipment to notify the user equipment of information on the radioresources allocated to the user equipment (S850).

At the step S830, the user equipment may calculate ePH for the power ofthe PUSCH to calculate the first type ePH. At this time, the userequipment may calculate the first type ePH by using the Equation 1.However, parameters at a random subframe i of the serving cell callocated to the user equipment are used as the parameters of theEquation 1.

At the step S830, the user equipment may calculate ePH for the sum (thatis, the sum of PH of the PUSCH and the PUCCH) of the power of the PUSCHand the power of the PUCCH to calculate the second type ePH.

Hereinafter, a method for calculating the second type ePH will bedescribed in detail. The following Equation 2 illustrates one offormulas for calculating the second type ePH.

PH _(SUM)(i)=P _(CMAXc)−10 log₁₀(10^(P) ^(PUSCHc)_scheduled^((i)/10)+10^(P) ^(PUCCH) _scheduled^((i)/10))

In the Equation 2, the user equipment calculates ePH by using the amountof power P_(PUSCHc) _(—) _(scheduled)(i) of the PUSCH and the amount ofpower P_(PUCCHc) _(—) _(scheduled)(i) of the PUCCH. In other words, theuser equipment may calculate one ePH value using the sum of the powerfor the PUSCH and the power for the PUCCH. The Equation 2 illustratesthat the user equipment transmits the PUSCH signal and the PUCCH signalfor the same subframe at the same time.

The following Equation 3 illustrates a formula for calculating theamount of power of the PUSCH used to calculate the second type ePH.

P _(PUSCHc) _(—) _(scheduled)(i)=10 log₁₀(M _(PUSCHc)(i))+P _(O) _(—)_(PUSCHc)(j)+α(j)·PL+Δ _(TFc)(i)+f _(c)(i)}  [Equation 3]

In this case, P_(CMAX) represents the theoretical maximum transmissionpower of the user equipment in the P cell or serving cell, andM_(PUSCH)(i) is a parameter indicating a bandwidth of PUSCH resourceallocation expressed as the number of effective resource blocks for thesubframe of index i and is a value allocated from the base station.

P_(O) _(—) _(PUSCH)(j) is a parameter configured by the sum of acell-specific nominal component P_(O) _(—) _(NOMINAL) _(—) _(PUSCH)(j)provided from the upper layer and a user equipment-specific componentP_(O) _(—) _(UE) _(—) _(PUSCH)(j) provided from the upper layer, and isa value notified from the base station to the user equipment.

α(j) is a cell-specific parameter provided from the upper layer andtransmitted by the base station as 3 bits, and when j=0 or 1, αε{0, 0.4,0.5, 0.6, 0.7, 0.8, 0.9, 1}, and when j=2, α(j)=1. α(j) is a valuenotified from the base station to the user equipment.

PL is an estimated value of downlink path loss (PL: PathLoss) calculatedby the user equipment in a unit of dB, and is expressed asPL=referenceSignalPower−higher layer filteredRSRP. f(i) is a valueindicating the current PUSCH power control adjustment state, and may beexpressed as a current absolute value or accumulated value.

The following Equation 4 illustrates one of formulas for calculating theamount of power of the PUCCH used in the Equation 2.

P _(PUCCH) _(—) _(scheduled)(i)=P _(O) _(—) _(PUCCH)(j)+PL+h(n _(CQI) ,n_(HARQ))+_(F) _(—) _(PUCCH)(F)+g(i)  [Equation 4]

The following Equation 5 illustrates another one of formulas forcalculating the amount of power of the PUCCH used in the Equation 2.

P _(PUCCH) _(—) _(scheduled)(i)=P _(O) _(—) _(PUCCH)(j)+PL+h(n _(CQI) ,n_(HARQ) ,n _(SR))+Δ_(F) _(—) _(PUCCH)(F)+ΔT×D(F′)+g(i)  [Equation 5]

In the Equations 4 and 5, Δ_(F) _(—) _(PUCCH) (F) is a parameterprovided from the upper layer of the user equipment to the physicallayer, and each Δ_(F) _(—) _(PUCCH) (F) value corresponds to a PUCCHformat (F) related to the PUCCH format 1a.

If the user equipment transmits the PUCCH on two antenna ports from theupper layer, ΔT×D(F′) value is provided from each upper layer, wherePUCCH format F′ is defined, to the lower layer.

h(n_(CQI),n_(HARQ)) and h(n_(CQI),n_(HARQ),n_(SR)) are subjected to thePUCCH format, wherein n_(CQI) corresponds to the number of informationbits for CQI. If the subframe i is configured for scheduling request forthe user equipment, n_(SR) is set to 1. If not so, n_(SR) is set to 0.n_(HARQ) represents the number of HARQ bits or the number of transportblocks for the subframe i.

P_(O) _(—) _(PUCCH) represents a parameter configured by the sum ofparameters P_(O) _(—) _(NOMIMAL) _(—) _(PUCCH) and P_(O) _(—) _(UE) _(—)_(PUCCH) provided from the upper layer. Also, g(i) represents thecurrent PUCCH transmission control adjustment state value, and g(0)represents an initial value after re-establishment.

The following Equation 6 illustrates other one of formulas forcalculating the power rate of the PUCCH used in the Equation 2.

PH _(SUM)(i)=P _(CMAXc)−10 log₁₀(10^(P) ^(PUSCHc)_scheduled^((i)/10)+10^((P) ^(O) _PUCCH^((j)+PL+g(i))/10))  [Equation 6]

The Equation 6 illustrates a method for calculating ePH consideringPUCCH power rate even if the user equipment transmits a PUSCH signalonly without transmitting a PUCCH signal in a P cell. The Equation 6 isa method for obtaining PH for the sum of the power of the PUSCHcurrently transmitted and the PUCCH power except for offset related totransport format from the allocation power of the PUCCH. In other words,the amount of power of the PUCCH in the Equation 6 may be obtained by anopen-loop parameter P_(O) _(—) _(PUCCH)(j) of the PUCCH, a path losscompensation value PL of the ith subframe which is the current frame,and a closed-loop parameter value g(i) dynamically accumulated to reachthe i-th subframe. The description of each parameter will be understoodwith reference to the Equations 4 and 5.

5. Power Headroom Report Method II in Carrier Matching Environment

In the above chapter 4, the method for reporting ePHR to a base stationby calculating the first type ePH and the second type ePH has beendescribed. Hereinafter, in addition to the method described in thechapter 4, power headroom report methods in a carrier aggregationenvironment will be described. However, description of basic parametersor description of the transmission mode of the user equipment will beunderstood with reference to the description of the chapter 4.

If the user equipment is configured by the mode A, the PUSCH and thePUCCH may be simultaneously transmitted in an arbitrary subframe of anarbitrary serving cell. In this case, the base station should properlyallocate a PUSCH resource to one or more user equipments, and the userequipment preferably performs scheduling so as not to exceed the limitedtransmission power of the corresponding serving cell. To this end, as anextended power headroom report (ePHR) methods transmitted from the userequipment to the base station, the following three types of methods maybe considered.

(1) Each user equipment may transmit PUSCH power headroom informationand PUCCH power headroom information of the corresponding serving cellfor all the subframes for which the PHR of the user equipment should betransmitted, to the base station.

(2) As another method, the user equipment configured by the mode A maytransmit PUSCH PHR and PUCCH PHR of the P cell (UL CC1) to the basestation and notify the base station of PUSCH PHR information only in theS cell (UL CC2, UL CC3) in which the PUSCH is only transmitted.

If the user equipment is configured with the mode B, it does nottransmit the PUSCH signal and the PUCCH signal for a random subframe inthe PUSCH region and the PUCCH region at the same time to maintain thesingle carrier property. In this case, in the same manner the LTE system(R-8), since many RBs are not used by PUCCH transmission only of theuser equipment in the LTE-A system, it is not likely that power limit ofthe corresponding CC is exceeded. Also, since the PUCCH signal which isthe control signal is transmitted through the PUSCH region by beingsubjected to piggyback or multiplexing with the PUSCH signal which isthe data signal, the user equipment configured by the mode B may notreport power headroom for the PUCCH and may transmit the power headroominformation only on the PUSCH signal to the base station.

Accordingly, if the user equipment is configured with the mode A, it maytransmit the PUSCH and the PUCCH for the same subframe in the P cell. Inother words, the user equipment transmits the PUSCH signal and the PUCCHsignal in the P cell at the same time. In this case, it is preferablethat the user equipment transmits the PHR for the sum of the PHR of thePUSCH and the PHR of the PUCCH to the base station.

If the user equipment is configured with the mode B, the PUCCH signalmay be transmitted by being subjected to piggyback or multiplexing withthe PUSCH signal as shown in FIG. 7( b) for the subframe where the PUSCHsignal and the PUCCH signal should be transmitted. In this case, theuser equipment has only to transmit the PHR for the PUSCH to the basestation.

Also, unlike the aforementioned methods, even though the PUSCH signaland the PUCCH signal are not transmitted at the same time for thecurrent (ith) subframe, a method for reporting ePH for the sum of thePUSCH power rate and the PUCCH power rate may be considered. In otherwords, even though the PUSCH signal is only transmitted, the userequipment may report ePH for the sum of the PUSCH power rate and thePUCCH power rate.

The following Equation 7 illustrates another one of methods forcalculating ePH for the sum of the PUSCH power rate and the PUCCH powerrate.

PH _(SUM)(i)=P _(CMAXc)−10 log₁₀(10^(P) ^(PUSCHc)_scheduled^((i)/10)+10^(P) ^(PUCCH) _scheduled^((k)/10))  [Equation 7]

The Equation 7 illustrates a method for obtaining power headroom (PH) ofthe user equipment for the sum value of the PUSCH power currentlytransmitted (i-th subframe) and the PUCCH power most recentlytransmitted. In other words, in the Equation 7, the PUCCH power is forthe k-th (for example, k<i) subframe.

FIG. 9 is a diagram illustrating an example of an apparatus forsupporting a method for reporting power headroom, which is disclosed inthe present invention, in accordance with the embodiment of the presentinvention.

Referring to FIG. 9, a wireless communication system may include one ormore base stations 10 and one ore more user equipments 20. In adownlink, a transmitter is operated as a part of the base station 10,and a receiver is operated as a part of the user equipment 20. In anuplink, the transmitter is operated as a part of the user equipment 20,and the receiver is operated as a part of the base station 10.

The base station 10 may include a processor 11, a memory 12, and a radiofrequency (RF) unit 13. The processor 11 may be configured to implementprocedures and/or methods suggested in the present invention. Forexample, the processor 11 of the base station may perform uplinkresource scheduling considering PHR received from the user equipment anduplink resource scheduling and allocation functions for the userequipment. The memory 12 is connected with the processor 11 and storesvarious kinds of information related to the operation of the processor11. The RF unit 13 is connected with the processor 11 and transmitsand/or receives a radio signal.

The user equipment 20 may include a processor 21, a memory 22, and aradio frequency (RF) unit 23. The processor 21 may be configured toimplement procedures and/or methods suggested in the present invention.For example, the processor of the user equipment may decode the PDCCHtransmitted thereto by monitoring a search space using the RF unit andacquire information on uplink resources allocated thereto by detecting aDCI format included in the PDCCH. Also, the processor of the userequipment may calculate a power rate for the subframe and a powerheadroom value based on the transmission mode, and may report thecalculated values to the base station. The memory 22 is connected withthe processor 21 and stores various kinds of information related to theoperation of the processor 21. The RF unit 23 is connected with theprocessor 21 and transmits and/or receives a radio signal.

The base station 10 and/or the user equipment 20 may have a singleantenna or multiple antennas. When at least one of the base station andthe user equipment has a plurality of antennas, the wirelesscommunication system may be referred to as a multi-input multi-output(MIMO) system.

FIG. 10 is a diagram illustrating another example of an apparatus forsupporting a method for reporting power headroom, which is disclosed inthe present invention, in accordance with the embodiment of the presentinvention.

The user equipment UE may be operated as a transmitter in an uplink andmay be operated as a receiver in a downlink. Also, the base station eNBmay be operated as a receiver in an uplink and may be operated as atransmitter in a downlink.

In other words, each of the user equipment and the base station mayinclude a transmission (Tx) module 1040, 1050 and a reception (Rx)module 1050, 1070 to control transmission and reception of data and/ormessage, and an antenna 1000, 1010 for transmitting and receivinginformation, data and/or message. Also, each of the user equipment andthe base station may include a processor 1020, 1030 for performing theaforementioned embodiments of the present invention and a memory 1080,1090 for temporarily or continuously storing a processing procedure ofthe processor.

In particular, the processor 1020, 1030 may perform second type ePHreport and first ePH report in accordance with the transmission modes Aand B of the user equipment in the carrier matching environmentdisclosed in the embodiments of the present invention. Also, the userequipment and the base station of FIG. 10 may further include a lowerpower RF (radio frequency)/IF (intermediate frequency) module.

The Tx module and the Rx module included in the user equipment and thebase station may perform a packet modulation and demodulation functionfor data transmission, a quick packet channel coding function, anorthogonal frequency division multiple access (OFDMA) packet scheduling,time division duplex (TDD) packet scheduling and/or channel multiplexingfunction.

The apparatus described in FIG. 10 is the means for implementing thevarious power headroom report methods disclosed in the presentinvention. The embodiments of the present invention may be performedusing the modules and functions of the user equipment and the basestation.

In the meantime, in the present invention, examples of the userequipment may include a personal digital assistant (PDA), a cellularphone, a personal communication service (PCS) phone, a global system formobile (GSM) phone, a wideband CDMA (WCDMA) phone, a mobile broadbandsystem (MBS) phone, a hand-held PC, a notebook PC, a smart phone, and amulti mode-multi band (MM-MB) terminal.

In this case, the smart phone is a terminal provided with advantages ofa mobile communication terminal and a personal digital assistant (PDA).The smart phone may mean a terminal in which a schedule managementfunction of the PDA and data communication functions of facsimiletransmission/reception, internet access, etc. are integrated on a mobilecommunication terminal. Also, the multimode-multiband terminal means aterminal having a built-in multi-MODEM chip to be operable in a portableinternet system and other mobile communication systems (e.g., CDMA (codedivision multiple access) 2000 system, WCDMA (wideband CDMA) system,etc.).

The embodiments according to the present invention may be implemented byvarious means, for example, hardware, firmware, software, or theircombination.

If the embodiment according to the present invention is implemented byhardware, the embodiments of the present invention may be implemented byone or more application specific integrated circuits (ASICs), digitalsignal processors (DSPs), digital signal processing devices (DSPDs),programmable logic devices (PLDs), field programmable gate arrays(FPGAs), processors, controllers, microcontrollers, microprocessors,etc.

If the embodiment according to the present invention is implemented byfirmware or software, the method according to the embodiments of thepresent invention may be implemented by a type of a module, a procedure,or a function, which performs functions or operations described asabove. For example, a software code may be stored in the memory unit1080, 1090 and then may be driven by the processor 1020, 1030. Thememory unit may be located inside or outside the processor to transmitand receive data to and from the processor through various means whichare well known.

Those skilled in the art will appreciate that the present invention maybe carried out in other specific ways than those set forth hereinwithout departing from the spirit and essential characteristics of thepresent invention. The above embodiments are therefore to be construedin all aspects as illustrative and not restrictive. The scope of theinvention should be determined by the appended claims and their legalequivalents, not by the above description, and all changes coming withinthe meaning and equivalency range of the appended claims are intended tobe embraced therein. It is also obvious to those skilled in the art thatclaims that are not explicitly cited in each other in the appendedclaims may be presented in combination as an embodiment of the presentinvention or included as a new claim by a subsequent amendment after theapplication is filed.

The aforementioned embodiments of the present invention may be appliedto various wireless access systems. Examples of the various wirelessaccess systems include 3GPP LTE system, 3GPP LTE-A system, 3GPP2 and/orIEEE 802.16m system. The embodiments of the present invention may beapplied to all the technical fields based on the various wireless accesssystems as well as the various wireless access systems.

What is claimed is:
 1. A method for reporting power headroom value in a wireless access system that supports a carrier aggregation, the method performed by a user equipment (UE) and comprising: receiving a uplink transmission grant allocating uplink resources on a predetermined subframe in an anchor uplink component carrier (UL CC); obtaining power headroom value for the anchor UL CC, if the UE is configured with a simultaneous physical uplink control channel (PUCCH) and physical uplink shared channel (PUSCH) transmission; and reporting the power headroom value to a base station, wherein the power headroom value is calculated by using: PH _(SUM)(i)=P _(CMAXc)−10 log₁₀(10^(P) ^(PUSCHc) _scheduled^((i)/10)+10^(P) ^(PUCCH) _scheduled^((i)/10)), where P_(CMAXc) represents the maximum transmission power of the UE, P_(PUSCH) _(—) _(scheduled)(i) represents a transmission power for the PUSCH, and P_(PUCCH) _(—) _(scheduled)(i) represents a transmission power for the PUCCH, and wherein ‘i’ is an index of the predetermined subframe and ‘c’ is an index of the anchor UL CC.
 2. The method according to claim 1, further comprising: transmitting the PUCCH on the predetermined subframe in the anchor UL CC.
 3. The method according to claim 1, wherein the uplink transmission grant is received via a physical downlink control channel (PDCCH).
 4. The method according to claim 1, wherein the anchor UL CC is a primary cell.
 5. A user equipment (UE) for reporting power headroom value in a wireless access system that supports a carrier aggregation, the UE comprising: a transmitter; a receiver; and a processor configured to: report the power headroom value by controlling the transmitter and the receiver, receive, by controlling the receiver, a uplink transmission grant allocating uplink resources on a predetermined subframe in an anchor uplink component carrier (UL CC), obtain power headroom value for the anchor UL CC, if the UE is configured with a simultaneous physical uplink control channel (PUCCH) and physical uplink shared channel (PUSCH) transmission, and report, by controlling the transmitter, the power headroom value to a base station, wherein the power headroom value is calculated by using: PH _(SUM)(i)=P _(CMAXc)−10 log₁₀(10^(P) ^(PUSCHc) _scheduled^((i)/10)+10^(P) ^(PUCCH) _scheduled^((i)/10)), where P_(CMAXc) represents the maximum transmission power of the UE, P_(PUSCH) _(—) _(scheduled)(i) represents a transmission power for the PUSCH, and P_(PUCCH) _(—) _(scheduled)(i) represents a transmission power for the PUCCH, and wherein ‘i’ is an index of the predetermined subframe and ‘c’ is an index of the anchor UL CC.
 6. The UE according to claim 5, wherein the processor is further configured to: transmit, by controlling the transmitter, the PUCCH on the predetermined subframe in the anchor UL CC.
 7. The UE according to claim 5, wherein the uplink transmission grant is received via a physical downlink control channel (PDCCH).
 8. The UE according to claim 5, wherein the anchor UL CC is a primary cell. 